MICROWAVE SPECTROSCOPY OF ISOTOPICALLY SUBSTITUTED HCCN AND ITS MOLECULAR-STRUCTURE

Rotational transitions of the isotopically substituted HCCN radicals, DCCN, H13CCN, HC13CN, and HCC15N, were studied by using a source-modulated microwave spectrometer combined with a glow-discharge free space cell. The rotational constant, the centrifugal distortion constant, the spin-spin coupling constant with its centrifugal distortion term, and the spin-rotation coupling constant were precisely determined for the four isotopic species. From the observed rotational constants of the four species and from that of the normal species previously reported, the rs structure was determined: r(CH) = 0.998 A ̊, r(CC) = 1.323 A ̊, and r(CN) = 1.195 A ̊. © 1990.